path: root/src/fs/io/GunzipReader.cxx

/*
 * Copyright (C) 2003-2014 The Music Player Daemon Project
 * http://www.musicpd.org
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "config.h"
#include "GunzipReader.hxx"
#include "util/Error.hxx"
#include "util/Domain.hxx"

const Domain zlib_domain("zlib");

GunzipReader::GunzipReader(Reader &_next, Error &error)
	:next(_next), eof(false)
{
	z.next_in = nullptr;
	z.avail_in = 0;
	z.zalloc = Z_NULL;
	z.zfree = Z_NULL;
	z.opaque = Z_NULL;

	int result = inflateInit2(&z, 16 + MAX_WBITS);
	if (result != Z_OK) {
		z.opaque = this;
		error.Set(zlib_domain, result, zError(result));
	}
}

GunzipReader::~GunzipReader()
{
	if (IsDefined())
		inflateEnd(&z);
}

inline bool
GunzipReader::FillBuffer(Error &error)
{
	auto w = buffer.Write();
	assert(!w.IsEmpty());

	size_t nbytes = next.Read(w.data, w.size, error);
	if (nbytes == 0)
		return false;

	buffer.Append(nbytes);
	return true;
}

size_t
GunzipReader::Read(void *data, size_t size, Error &error)
{
	if (eof)
		return 0;

	z.next_out = (Bytef *)data;
	z.avail_out = size;

	while (true) {
		int flush = Z_NO_FLUSH;

		auto r = buffer.Read();
		if (r.IsEmpty()) {
			if (FillBuffer(error))
				r = buffer.Read();
			else if (error.IsDefined())
				return 0;
			else
				flush = Z_FINISH;
		}

		z.next_in = r.data;
		z.avail_in = r.size;

		int result = inflate(&z, flush);
		if (result == Z_STREAM_END) {
			eof = true;
			return size - z.avail_out;
		} else if (result != Z_OK) {
			error.Set(zlib_domain, result, zError(result));
			return 0;
		}

		buffer.Consume(r.size - z.avail_in);

		if (z.avail_out < size)
			return size - z.avail_out;
	}
}